为什么我不能在BinarySearchTree中找到_left和_right？

I'm having a problem with the following code snippet:

我遇到以下代码段的问题:

using System;
using System.Collections.Generic;
using System.Text;

namespace trees_by_firas
{
    class Program
    {
        static void Main(string[] args)
        {
            BinarySearchTree t = new BinarySearchTree();

            t.insert(ref t.root, 10);
            t.insert(ref t.root, 5);
            t.insert(ref t.root, 6);
            t.insert(ref t.root, 17);
            t.insert(ref t.root, 2);
            t.insert(ref t.root, 3);

            BinarySearchTree.print(t.root);
            Console.WriteLine("--------------------");
            Console.WriteLine(t.FindMax());
            Console.WriteLine(t.FindMin());
            Console.WriteLine("--------------------");
            Console.WriteLine(t.CountLeaves());
            Console.WriteLine(t.CountNodes());



        }

        public class TreeNode
        {
            public int n;
            public TreeNode _left;
            public TreeNode _right;


            public TreeNode(int n, TreeNode _left, TreeNode _right)
            {
                this.n = n;
                this._left = _left;
                this._right = _right;
            }


            public void DisplayNode()
            {
                Console.Write(n);
            }


        }


        public class BinarySearchTree
        {
            public TreeNode root;


            public BinarySearchTree()
            {
                root = null;
            }


            public void insert(ref TreeNode root, int x)
            {
                if (root == null)
                {
                    root = new TreeNode(x, null, null);
                }
                else
                    if (x < root.n)
                        insert(ref root._left, x);
                    else
                        insert(ref root._right, x);
            }

            public int FindMin()
            {
                TreeNode current = root;

                while (current._left != null)
                    current = current._left;

                return current.n;
            }

            public int FindMax()
            {
                TreeNode current = root;

                while (current._right != null)
                    current = current._right;

                return current.n;
            }



            public TreeNode Find(int key)
            {
                TreeNode current = root;

                while (current.n != key)
                {
                    if (key < current.n)
                        current = current._left;
                    else
                        current = current._right;
                    if (current == null)
                        return null;
                }
                return current;
            }



            public void InOrder(ref TreeNode root)
            {
                if (root != null)
                {
                    InOrder(ref root._left);
                    root.DisplayNode();
                    InOrder(ref root._right);
                }
            }

            public int CountNodes()
            {
                int count = 1; // me!        
                if (root._left != null)
                    count += _left.CountNodes();
                if (root._right != null)
                    count += _right.CountNodes();
                return count;
            }

            public int CountLeaves()
            {
                int count = (root._left == null && root._right == null) ? 1 : 0;
                if (root._left != null)
                    count += _left.CountLeaves();
                if (root._right != null)
                    count += _right.CountLeaves();
                return count;
            }

            public static void print(TreeNode root)
            {
                if (root != null)
                {
                    print(root._left);
                    Console.WriteLine(root.n.ToString());
                    print(root._right);
                }

            }



        }

    }
}

I get the following errors:

我收到以下错误:

Error 1 The name '_left' does not exist in the current context 

// on the countnodes & countleaves

Error 2 The name '_right' does not exist in the current context 
// on the countnodes & countleaves

Any thoughts on how I can fix these errors?

有关如何解决这些错误的任何想法?

2 个解决方案

#1

_left and _right are fields in TreeNode. You're trying to use them as if they're part of BinarySearchTree. I believe you can just prefix them with root.:

_left和_right是TreeNode中的字段。你试图使用它们就像它们是BinarySearchTree的一部分一样。我相信你可以用root作为前缀:

public int CountNodes()
{
    int count = 1; // me!        
    if (root._left != null)
        count += root._left.CountNodes();
    if (root._right != null)
        count += root._right.CountNodes();
    return count;
}

public int CountLeaves()
{
    int count = (root._left == null && root._right == null) ? 1 : 0;
    if (root._left != null)
        count += root._left.CountLeaves();
    if (root._right != null)
        count += root._right.CountLeaves();
    return count;
}

#2

I get quite the opposite result from your code - 6 nodes and 3 leaves. 6 nodes is the number of items you have inserted into the tree, so this makes sense. The number of leaves should be the number of nodes in the tree having no children. As your tree currently looks like this...

我从你的代码得到了相反的结果 - 6个节点和3个叶子。 6个节点是您插入树中的项目数,因此这是有道理的。叶子的数量应该是树中没有子节点的节点数。因为你的树目前看起来像这样......

...you have six nodes and three leaves (17,6 and 3).

...你有六个节点和三个叶子(17,6和3)。

#1